Several people were injured in a dispute between two groups with firearms and stabbing weapons in Dortmund.
There was therefore a large-scale police operation on Sunday, several streets were closed.
Two groups of people ran into each other on a sidewalk on Sunday afternoon, the police said.
There were also arrests after the confrontation.
How many injured and arrested there were and what the background to the dispute had is currently being investigated.
"The investigation is proceeding swiftly."
In the evening the crime scene was examined.
A police spokeswoman said: "We are there with strong forces." According to the police, there was no longer any danger for the population.
At the beginning, bystanders were asked to avoid the area around the scene of the incident.
him / dpa